// Copyright (C) 2024 EA group inc.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//

#include <turbo/flags/cli/app.h>
#include <turbo/flags/cli/argv.h>
#include <turbo/flags/cli/encoding.h>
#include <algorithm>
#include <memory>
#include <string>
#include <utility>
#include <vector>

namespace turbo::cli {

    App::App(std::string app_description, std::string app_name, App *parent)
            : name_(std::move(app_name)), description_(std::move(app_description)), parent_(parent) {
        // Inherit if not from a nullptr
        if (parent_ != nullptr) {
            if (parent_->help_ptr_ != nullptr)
                set_help_flag(parent_->help_ptr_->get_name(false, true), parent_->help_ptr_->get_description());
            if (parent_->help_all_ptr_ != nullptr)
                set_help_all_flag(parent_->help_all_ptr_->get_name(false, true),
                                  parent_->help_all_ptr_->get_description());

            /// OptionDefaults
            option_defaults_ = parent_->option_defaults_;

            // INHERITABLE
            failure_message_ = parent_->failure_message_;
            allow_extras_ = parent_->allow_extras_;
            allow_config_extras_ = parent_->allow_config_extras_;
            prefix_command_ = parent_->prefix_command_;
            immediate_callback_ = parent_->immediate_callback_;
            ignore_case_ = parent_->ignore_case_;
            ignore_underscore_ = parent_->ignore_underscore_;
            fallthrough_ = parent_->fallthrough_;
            validate_positionals_ = parent_->validate_positionals_;
            validate_optional_arguments_ = parent_->validate_optional_arguments_;
            configurable_ = parent_->configurable_;
            allow_windows_style_options_ = parent_->allow_windows_style_options_;
            group_ = parent_->group_;
            usage_ = parent_->usage_;
            footer_ = parent_->footer_;
            formatter_ = parent_->formatter_;
            config_formatter_ = parent_->config_formatter_;
            require_subcommand_max_ = parent_->require_subcommand_max_;
        }
    }

    [[nodiscard]] char **App::ensure_utf8(char **argv) {
#ifdef _WIN32
        (void)argv;

        normalized_argv_ = detail::compute_win32_argv();

        if(!normalized_argv_view_.empty()) {
            normalized_argv_view_.clear();
        }

        normalized_argv_view_.reserve(normalized_argv_.size());
        for(auto &arg : normalized_argv_) {
            // using const_cast is well-defined, string is known to not be const.
            normalized_argv_view_.push_back(const_cast<char *>(arg.data()));
        }

        return normalized_argv_view_.data();
#else
        return argv;
#endif
    }

    App *App::name(std::string app_name) {

        if (parent_ != nullptr) {
            std::string oname = name_;
            name_ = app_name;
            const auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
            if (!res.empty()) {
                name_ = oname;
                throw (OptionAlreadyAdded(app_name + " conflicts with existing subcommand names"));
            }
        } else {
            name_ = app_name;
        }
        has_automatic_name_ = false;
        return this;
    }

    App *App::alias(std::string app_name) {
        if (app_name.empty() || !detail::valid_alias_name_string(app_name)) {
            throw IncorrectConstruction("Aliases may not be empty or contain newlines or null characters");
        }
        if (parent_ != nullptr) {
            aliases_.push_back(app_name);
            const auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
            if (!res.empty()) {
                aliases_.pop_back();
                throw (OptionAlreadyAdded("alias already matches an existing subcommand: " + app_name));
            }
        } else {
            aliases_.push_back(app_name);
        }

        return this;
    }

    App *App::immediate_callback(bool immediate) {
        immediate_callback_ = immediate;
        if (immediate_callback_) {
            if (final_callback_ && !(parse_complete_callback_)) {
                std::swap(final_callback_, parse_complete_callback_);
            }
        } else if (!(final_callback_) && parse_complete_callback_) {
            std::swap(final_callback_, parse_complete_callback_);
        }
        return this;
    }

    App *App::ignore_case(bool value) {
        if (value && !ignore_case_) {
            ignore_case_ = true;
            auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
            const auto &match = _compare_subcommand_names(*this, *p);
            if (!match.empty()) {
                ignore_case_ = false;  // we are throwing so need to be exception invariant
                throw OptionAlreadyAdded("ignore case would cause subcommand name conflicts: " + match);
            }
        }
        ignore_case_ = value;
        return this;
    }

    App *App::ignore_underscore(bool value) {
        if (value && !ignore_underscore_) {
            ignore_underscore_ = true;
            auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
            const auto &match = _compare_subcommand_names(*this, *p);
            if (!match.empty()) {
                ignore_underscore_ = false;
                throw OptionAlreadyAdded("ignore underscore would cause subcommand name conflicts: " + match);
            }
        }
        ignore_underscore_ = value;
        return this;
    }

    Option *App::add_option(std::string option_name,
                            callback_t option_callback,
                            std::string option_description,
                            bool defaulted,
                            std::function<std::string()> func) {
        Option myopt{option_name, option_description, option_callback, this};

        if (std::find_if(std::begin(options_), std::end(options_),
                         [&myopt](const Option_p &v) { return *v == myopt; }) ==
            std::end(options_)) {
            if (myopt.lnames_.empty() && myopt.snames_.empty()) {
                // if the option is positional only there is additional potential for ambiguities in config files and needs
                // to be checked
                std::string test_name = "--" + myopt.get_single_name();
                if (test_name.size() == 3) {
                    test_name.erase(0, 1);
                }

                auto *op = get_option_no_throw(test_name);
                if (op != nullptr) {
                    throw (OptionAlreadyAdded("added option positional name matches existing option: " + test_name));
                }
            } else if (parent_ != nullptr) {
                for (auto &ln: myopt.lnames_) {
                    auto *op = parent_->get_option_no_throw(ln);
                    if (op != nullptr) {
                        throw (OptionAlreadyAdded("added option matches existing positional option: " + ln));
                    }
                }
                for (auto &sn: myopt.snames_) {
                    auto *op = parent_->get_option_no_throw(sn);
                    if (op != nullptr) {
                        throw (OptionAlreadyAdded("added option matches existing positional option: " + sn));
                    }
                }
            }
            options_.emplace_back();
            Option_p &option = options_.back();
            option.reset(new Option(option_name, option_description, option_callback, this));

            // Set the default string capture function
            option->default_function(func);

            // For compatibility with CLI11 1.7 and before, capture the default string here
            if (defaulted)
                option->capture_default_str();

            // Transfer defaults to the new option
            option_defaults_.copy_to(option.get());

            // Don't bother to capture if we already did
            if (!defaulted && option->get_always_capture_default())
                option->capture_default_str();

            return option.get();
        }
        // we know something matches now find what it is so we can produce more error information
        for (auto &opt: options_) {
            const auto &matchname = opt->matching_name(myopt);
            if (!matchname.empty()) {
                throw (OptionAlreadyAdded("added option matched existing option name: " + matchname));
            }
        }
        // this line should not be reached the above loop should trigger the throw
        throw (OptionAlreadyAdded("added option matched existing option name"));  // LCOV_EXCL_LINE
    }

    Option *App::set_help_flag(std::string flag_name, const std::string &help_description) {
        // take flag_description by const reference otherwise add_flag tries to assign to help_description
        if (help_ptr_ != nullptr) {
            remove_option(help_ptr_);
            help_ptr_ = nullptr;
        }

        // Empty name will simply remove the help flag
        if (!flag_name.empty()) {
            help_ptr_ = add_flag(flag_name, help_description);
            help_ptr_->configurable(false);
        }

        return help_ptr_;
    }

    Option *App::set_help_all_flag(std::string help_name, const std::string &help_description) {
        // take flag_description by const reference otherwise add_flag tries to assign to flag_description
        if (help_all_ptr_ != nullptr) {
            remove_option(help_all_ptr_);
            help_all_ptr_ = nullptr;
        }

        // Empty name will simply remove the help all flag
        if (!help_name.empty()) {
            help_all_ptr_ = add_flag(help_name, help_description);
            help_all_ptr_->configurable(false);
        }

        return help_all_ptr_;
    }

    Option *
    App::set_version_flag(std::string flag_name, const std::string &versionString, const std::string &version_help) {
        // take flag_description by const reference otherwise add_flag tries to assign to version_description
        if (version_ptr_ != nullptr) {
            remove_option(version_ptr_);
            version_ptr_ = nullptr;
        }

        // Empty name will simply remove the version flag
        if (!flag_name.empty()) {
            version_ptr_ = add_flag_callback(
                    flag_name, [versionString]() { throw (turbo::cli::CallForVersion(versionString, 0)); },
                    version_help);
            version_ptr_->configurable(false);
        }

        return version_ptr_;
    }

    Option *
    App::set_version_flag(std::string flag_name, std::function<std::string()> vfunc, const std::string &version_help) {
        if (version_ptr_ != nullptr) {
            remove_option(version_ptr_);
            version_ptr_ = nullptr;
        }

        // Empty name will simply remove the version flag
        if (!flag_name.empty()) {
            version_ptr_ =
                    add_flag_callback(flag_name, [vfunc]() { throw (turbo::cli::CallForVersion(vfunc(), 0)); },
                                      version_help);
            version_ptr_->configurable(false);
        }

        return version_ptr_;
    }

    Option *App::_add_flag_internal(std::string flag_name, turbo::cli::callback_t fun, std::string flag_description) {
        Option *opt = nullptr;
        if (detail::has_default_flag_values(flag_name)) {
            // check for default values and if it has them
            auto flag_defaults = detail::get_default_flag_values(flag_name);
            detail::remove_default_flag_values(flag_name);
            opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
            for (const auto &fname: flag_defaults)
                opt->fnames_.push_back(fname.first);
            opt->default_flag_values_ = std::move(flag_defaults);
        } else {
            opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
        }
        // flags cannot have positional values
        if (opt->get_positional()) {
            auto pos_name = opt->get_name(true);
            remove_option(opt);
            throw IncorrectConstruction::PositionalFlag(pos_name);
        }
        opt->multi_option_policy(MultiOptionPolicy::TakeLast);
        opt->expected(0);
        opt->required(false);
        return opt;
    }

    Option *App::add_flag_callback(std::string flag_name,
                                   std::function<void(void)> function,  ///< A function to call, void(void)
                                   std::string flag_description) {

        turbo::cli::callback_t fun = [function](const turbo::cli::results_t &res) {
            using turbo::cli::detail::lexical_cast;
            bool trigger{false};
            auto result = lexical_cast(res[0], trigger);
            if (result && trigger) {
                function();
            }
            return result;
        };
        return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
    }

    Option *
    App::add_flag_function(std::string flag_name,
                           std::function<void(std::int64_t)> function,  ///< A function to call, void(int)
                           std::string flag_description) {

        turbo::cli::callback_t fun = [function](const turbo::cli::results_t &res) {
            using turbo::cli::detail::lexical_cast;
            std::int64_t flag_count{0};
            lexical_cast(res[0], flag_count);
            function(flag_count);
            return true;
        };
        return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
                ->multi_option_policy(MultiOptionPolicy::Sum);
    }

    Option *App::set_config(std::string option_name,
                            std::string default_filename,
                            const std::string &help_message,
                            bool config_required) {

        // Remove existing config if present
        if (config_ptr_ != nullptr) {
            remove_option(config_ptr_);
            config_ptr_ = nullptr;  // need to remove the config_ptr completely
        }

        // Only add config if option passed
        if (!option_name.empty()) {
            config_ptr_ = add_option(option_name, help_message);
            if (config_required) {
                config_ptr_->required();
            }
            if (!default_filename.empty()) {
                config_ptr_->default_str(std::move(default_filename));
                config_ptr_->force_callback_ = true;
            }
            config_ptr_->configurable(false);
            // set the option to take the last value and reverse given by default
            config_ptr_->multi_option_policy(MultiOptionPolicy::Reverse);
        }

        return config_ptr_;
    }

    bool App::remove_option(Option *opt) {
        // Make sure no links exist
        for (Option_p &op: options_) {
            op->remove_needs(opt);
            op->remove_excludes(opt);
        }

        if (help_ptr_ == opt)
            help_ptr_ = nullptr;
        if (help_all_ptr_ == opt)
            help_all_ptr_ = nullptr;

        auto iterator =
                std::find_if(std::begin(options_), std::end(options_),
                             [opt](const Option_p &v) { return v.get() == opt; });
        if (iterator != std::end(options_)) {
            options_.erase(iterator);
            return true;
        }
        return false;
    }

    App *App::add_subcommand(std::string subcommand_name, std::string subcommand_description) {
        if (!subcommand_name.empty() && !detail::valid_name_string(subcommand_name)) {
            if (!detail::valid_first_char(subcommand_name[0])) {
                throw IncorrectConstruction(
                        "Subcommand name starts with invalid character, '!' and '-' and control characters");
            }
            for (auto c: subcommand_name) {
                if (!detail::valid_later_char(c)) {
                    throw IncorrectConstruction(std::string("Subcommand name contains invalid character ('") + c +
                                                "'), all characters are allowed except"
                                                "'=',':','{','}', ' ', and control characters");
                }
            }
        }
        turbo::cli::App_p subcom = std::shared_ptr<App>(
                new App(std::move(subcommand_description), subcommand_name, this));
        return add_subcommand(std::move(subcom));
    }

    App *App::add_subcommand(turbo::cli::App_p subcom) {
        if (!subcom)
            throw IncorrectConstruction("passed App is not valid");
        auto *ckapp = (name_.empty() && parent_ != nullptr) ? _get_fallthrough_parent() : this;
        const auto &mstrg = _compare_subcommand_names(*subcom, *ckapp);
        if (!mstrg.empty()) {
            throw (OptionAlreadyAdded("subcommand name or alias matches existing subcommand: " + mstrg));
        }
        subcom->parent_ = this;
        subcommands_.push_back(std::move(subcom));
        return subcommands_.back().get();
    }

    bool App::remove_subcommand(App *subcom) {
        // Make sure no links exist
        for (App_p &sub: subcommands_) {
            sub->remove_excludes(subcom);
            sub->remove_needs(subcom);
        }

        auto iterator = std::find_if(
                std::begin(subcommands_), std::end(subcommands_),
                [subcom](const App_p &v) { return v.get() == subcom; });
        if (iterator != std::end(subcommands_)) {
            subcommands_.erase(iterator);
            return true;
        }
        return false;
    }

    App *App::get_subcommand(const App *subcom) const {
        if (subcom == nullptr)
            throw OptionNotFound("nullptr passed");
        for (const App_p &subcomptr: subcommands_)
            if (subcomptr.get() == subcom)
                return subcomptr.get();
        throw OptionNotFound(subcom->get_name());
    }

    [[nodiscard]] App *App::get_subcommand(std::string subcom) const {
        auto *subc = _find_subcommand(subcom, false, false);
        if (subc == nullptr)
            throw OptionNotFound(subcom);
        return subc;
    }

    [[nodiscard]] App *App::get_subcommand_no_throw(std::string subcom) const noexcept {
        return _find_subcommand(subcom, false, false);
    }

    [[nodiscard]] App *App::get_subcommand(int index) const {
        if (index >= 0) {
            auto uindex = static_cast<unsigned>(index);
            if (uindex < subcommands_.size())
                return subcommands_[uindex].get();
        }
        throw OptionNotFound(std::to_string(index));
    }

    turbo::cli::App_p App::get_subcommand_ptr(App *subcom) const {
        if (subcom == nullptr)
            throw OptionNotFound("nullptr passed");
        for (const App_p &subcomptr: subcommands_)
            if (subcomptr.get() == subcom)
                return subcomptr;
        throw OptionNotFound(subcom->get_name());
    }

    [[nodiscard]] turbo::cli::App_p App::get_subcommand_ptr(std::string subcom) const {
        for (const App_p &subcomptr: subcommands_)
            if (subcomptr->check_name(subcom))
                return subcomptr;
        throw OptionNotFound(subcom);
    }

    [[nodiscard]] turbo::cli::App_p App::get_subcommand_ptr(int index) const {
        if (index >= 0) {
            auto uindex = static_cast<unsigned>(index);
            if (uindex < subcommands_.size())
                return subcommands_[uindex];
        }
        throw OptionNotFound(std::to_string(index));
    }

    [[nodiscard]] turbo::cli::App *App::get_option_group(std::string group_name) const {
        for (const App_p &app: subcommands_) {
            if (app->name_.empty() && app->group_ == group_name) {
                return app.get();
            }
        }
        throw OptionNotFound(group_name);
    }

    [[nodiscard]] std::size_t App::count_all() const {
        std::size_t cnt{0};
        for (const auto &opt: options_) {
            cnt += opt->count();
        }
        for (const auto &sub: subcommands_) {
            cnt += sub->count_all();
        }
        if (!get_name().empty()) {  // for named subcommands add the number of times the subcommand was called
            cnt += parsed_;
        }
        return cnt;
    }

    void App::clear() {

        parsed_ = 0;
        pre_parse_called_ = false;

        missing_.clear();
        parsed_subcommands_.clear();
        for (const Option_p &opt: options_) {
            opt->clear();
        }
        for (const App_p &subc: subcommands_) {
            subc->clear();
        }
    }

    void App::parse(int argc, const char *const *argv) { parse_char_t(argc, argv); }

    void App::parse(int argc, const wchar_t *const *argv) { parse_char_t(argc, argv); }

    namespace detail {

        // Do nothing or perform narrowing
        const char *maybe_narrow(const char *str) { return str; }

        std::string maybe_narrow(const wchar_t *str) { return narrow(str); }

    }  // namespace detail

    template<class CharT>
    void App::parse_char_t(int argc, const CharT *const *argv) {
        // If the name is not set, read from command line
        if (name_.empty() || has_automatic_name_) {
            has_automatic_name_ = true;
            name_ = detail::maybe_narrow(argv[0]);
        }

        std::vector<std::string> args;
        args.reserve(static_cast<std::size_t>(argc) - 1U);
        for (auto i = static_cast<std::size_t>(argc) - 1U; i > 0U; --i)
            args.emplace_back(detail::maybe_narrow(argv[i]));

        parse(std::move(args));
    }

    void App::parse(std::string commandline, bool program_name_included) {

        if (program_name_included) {
            auto nstr = detail::split_program_name(commandline);
            if ((name_.empty()) || (has_automatic_name_)) {
                has_automatic_name_ = true;
                name_ = nstr.first;
            }
            commandline = std::move(nstr.second);
        } else {
            detail::trim(commandline);
        }
        // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
        if (!commandline.empty()) {
            commandline = detail::find_and_modify(commandline, "=", detail::escape_detect);
            if (allow_windows_style_options_)
                commandline = detail::find_and_modify(commandline, ":", detail::escape_detect);
        }

        auto args = detail::split_up(std::move(commandline));
        // remove all empty strings
        args.erase(std::remove(args.begin(), args.end(), std::string{}), args.end());
        try {
            detail::remove_quotes(args);
        } catch (const std::invalid_argument &arg) {
            throw turbo::cli::ParseError(arg.what(), turbo::cli::ExitCodes::InvalidError);
        }
        std::reverse(args.begin(), args.end());
        parse(std::move(args));
    }

    void App::parse(std::wstring commandline, bool program_name_included) {
        parse(narrow(commandline), program_name_included);
    }

    void App::parse(std::vector<std::string> &args) {
        // Clear if parsed
        if (parsed_ > 0)
            clear();

        // parsed_ is incremented in commands/subcommands,
        // but placed here to make sure this is cleared when
        // running parse after an error is thrown, even by _validate or _configure.
        parsed_ = 1;
        _validate();
        _configure();
        // set the parent as nullptr as this object should be the top now
        parent_ = nullptr;
        parsed_ = 0;

        _parse(args);
        run_callback();
    }

    void App::parse(std::vector<std::string> &&args) {
        // Clear if parsed
        if (parsed_ > 0)
            clear();

        // parsed_ is incremented in commands/subcommands,
        // but placed here to make sure this is cleared when
        // running parse after an error is thrown, even by _validate or _configure.
        parsed_ = 1;
        _validate();
        _configure();
        // set the parent as nullptr as this object should be the top now
        parent_ = nullptr;
        parsed_ = 0;

        _parse(std::move(args));
        run_callback();
    }

    void App::parse_from_stream(std::istream &input) {
        if (parsed_ == 0) {
            _validate();
            _configure();
            // set the parent as nullptr as this object should be the top now
        }

        _parse_stream(input);
        run_callback();
    }

    int App::exit(const Error &e, std::ostream &out, std::ostream &err) const {

        /// Avoid printing anything if this is a turbo::cli::RuntimeError
        if (e.get_name() == "RuntimeError")
            return e.get_exit_code();

        if (e.get_name() == "CallForHelp") {
            out << help();
            return e.get_exit_code();
        }

        if (e.get_name() == "CallForAllHelp") {
            out << help("", AppFormatMode::All);
            return e.get_exit_code();
        }

        if (e.get_name() == "CallForVersion") {
            out << e.what() << '\n';
            return e.get_exit_code();
        }

        if (e.get_exit_code() != static_cast<int>(ExitCodes::Success)) {
            if (failure_message_)
                err << failure_message_(this, e) << std::flush;
        }

        return e.get_exit_code();
    }

    std::vector<const App *> App::get_subcommands(const std::function<bool(const App

                                                                           *)> &filter) const {
        std::vector<const App *> subcomms(subcommands_.size());

        std::transform(
                std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms),

                [](
                        const App_p &v
                ) {
                    return v.

                            get();
                }
        );

        if (filter) {
            subcomms.
                    erase(std::remove_if(std::begin(subcomms),
                                         std::end(subcomms),
                                         [&filter](const App *app) { return !filter(app); }),
                          std::end(subcomms)
            );
        }

        return
                subcomms;
    }

    std::vector<App *> App::get_subcommands(const std::function<bool(App *)> &filter) {
        std::vector<App *> subcomms(subcommands_.size());
        std::transform(
                std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms),
                [](const App_p &v) { return v.get(); });

        if (filter) {
            subcomms.erase(
                    std::remove_if(std::begin(subcomms), std::end(subcomms),
                                   [&filter](App *app) { return !filter(app); }),
                    std::end(subcomms));
        }

        return subcomms;
    }

    bool App::remove_excludes(Option *opt) {
        auto iterator = std::find(std::begin(exclude_options_), std::end(exclude_options_), opt);
        if (iterator == std::end(exclude_options_)) {
            return false;
        }
        exclude_options_.erase(iterator);
        return true;
    }

    bool App::remove_excludes(App *app) {
        auto iterator = std::find(std::begin(exclude_subcommands_), std::end(exclude_subcommands_), app);
        if (iterator == std::end(exclude_subcommands_)) {
            return false;
        }
        auto *other_app = *iterator;
        exclude_subcommands_.erase(iterator);
        other_app->remove_excludes(this);
        return true;
    }

    bool App::remove_needs(Option *opt) {
        auto iterator = std::find(std::begin(need_options_), std::end(need_options_), opt);
        if (iterator == std::end(need_options_)) {
            return false;
        }
        need_options_.erase(iterator);
        return true;
    }

    bool App::remove_needs(App *app) {
        auto iterator = std::find(std::begin(need_subcommands_), std::end(need_subcommands_), app);
        if (iterator == std::end(need_subcommands_)) {
            return false;
        }
        need_subcommands_.erase(iterator);
        return true;
    }

    [[nodiscard]] std::string App::help(std::string prev, AppFormatMode mode) const {
        if (prev.empty())
            prev = get_name();
        else
            prev += " " + get_name();

        // Delegate to subcommand if needed
        auto selected_subcommands = get_subcommands();
        if (!selected_subcommands.empty()) {
            return selected_subcommands.back()->help(prev, mode);
        }
        return formatter_->make_help(this, prev, mode);
    }

    [[nodiscard]] std::string App::version() const {
        std::string val;
        if (version_ptr_ != nullptr) {
            // copy the results for reuse later
            results_t rv = version_ptr_->results();
            version_ptr_->clear();
            version_ptr_->add_result("true");
            try {
                version_ptr_->run_callback();
            } catch (const turbo::cli::CallForVersion &cfv) {
                val = cfv.what();
            }
            version_ptr_->clear();
            version_ptr_->add_result(rv);
        }
        return val;
    }

    std::vector<const Option *> App::get_options(const std::function<bool(const Option *)> filter) const {
        std::vector<const Option *> options(options_.size());
        std::transform(
                std::begin(options_), std::end(options_), std::begin(options),
                [](const Option_p &val) { return val.get(); });

        if (filter) {
            options.erase(std::remove_if(std::begin(options),
                                         std::end(options),
                                         [&filter](const Option *opt) { return !filter(opt); }),
                          std::end(options));
        }

        return options;
    }

    std::vector<Option *> App::get_options(const std::function<bool(Option *)> filter) {
        std::vector<Option *> options(options_.size());
        std::transform(
                std::begin(options_), std::end(options_), std::begin(options),
                [](const Option_p &val) { return val.get(); });

        if (filter) {
            options.erase(
                    std::remove_if(std::begin(options), std::end(options),
                                   [&filter](Option *opt) { return !filter(opt); }),
                    std::end(options));
        }

        return options;
    }

    [[nodiscard]] Option *App::get_option_no_throw(std::string option_name) noexcept {
        for (Option_p &opt: options_) {
            if (opt->check_name(option_name)) {
                return opt.get();
            }
        }
        for (auto &subc: subcommands_) {
            // also check down into nameless subcommands
            if (subc->get_name().empty()) {
                auto *opt = subc->get_option_no_throw(option_name);
                if (opt != nullptr) {
                    return opt;
                }
            }
        }
        return nullptr;
    }

    [[nodiscard]] const Option *App::get_option_no_throw(std::string option_name) const noexcept {
        for (const Option_p &opt: options_) {
            if (opt->check_name(option_name)) {
                return opt.get();
            }
        }
        for (const auto &subc: subcommands_) {
            // also check down into nameless subcommands
            if (subc->get_name().empty()) {
                auto *opt = subc->get_option_no_throw(option_name);
                if (opt != nullptr) {
                    return opt;
                }
            }
        }
        return nullptr;
    }

    [[nodiscard]] std::string App::get_display_name(bool with_aliases) const {
        if (name_.empty()) {
            return std::string("[Option Group: ") + get_group() + "]";
        }
        if (aliases_.empty() || !with_aliases) {
            return name_;
        }
        std::string dispname = name_;
        for (const auto &lalias: aliases_) {
            dispname.push_back(',');
            dispname.push_back(' ');
            dispname.append(lalias);
        }
        return dispname;
    }

    [[nodiscard]] bool App::check_name(std::string name_to_check) const {
        std::string local_name = name_;
        if (ignore_underscore_) {
            local_name = detail::remove_underscore(name_);
            name_to_check = detail::remove_underscore(name_to_check);
        }
        if (ignore_case_) {
            local_name = detail::to_lower(name_);
            name_to_check = detail::to_lower(name_to_check);
        }

        if (local_name == name_to_check) {
            return true;
        }
        for (std::string les: aliases_) {  // NOLINT(performance-for-range-copy)
            if (ignore_underscore_) {
                les = detail::remove_underscore(les);
            }
            if (ignore_case_) {
                les = detail::to_lower(les);
            }
            if (les == name_to_check) {
                return true;
            }
        }
        return false;
    }

    [[nodiscard]] std::vector<std::string> App::get_groups() const {
        std::vector<std::string> groups;

        for (const Option_p &opt: options_) {
            // Add group if it is not already in there
            if (std::find(groups.begin(), groups.end(), opt->get_group()) == groups.end()) {
                groups.push_back(opt->get_group());
            }
        }

        return groups;
    }

    [[nodiscard]] std::vector<std::string> App::remaining(bool recurse) const {
        std::vector<std::string> miss_list;
        for (const std::pair<detail::Classifier, std::string> &miss: missing_) {
            miss_list.push_back(std::get<1>(miss));
        }
        // Get from a subcommand that may allow extras
        if (recurse) {
            if (!allow_extras_) {
                for (const auto &sub: subcommands_) {
                    if (sub->name_.empty() && !sub->missing_.empty()) {
                        for (const std::pair<detail::Classifier, std::string> &miss: sub->missing_) {
                            miss_list.push_back(std::get<1>(miss));
                        }
                    }
                }
            }
            // Recurse into subcommands

            for (const App *sub: parsed_subcommands_) {
                std::vector<std::string> output = sub->remaining(recurse);
                std::copy(std::begin(output), std::end(output), std::back_inserter(miss_list));
            }
        }
        return miss_list;
    }

    [[nodiscard]] std::vector<std::string> App::remaining_for_passthrough(bool recurse) const {
        std::vector<std::string> miss_list = remaining(recurse);
        std::reverse(std::begin(miss_list), std::end(miss_list));
        return miss_list;
    }

    [[nodiscard]] std::size_t App::remaining_size(bool recurse) const {
        auto remaining_options = static_cast<std::size_t>(std::count_if(
                std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string> &val) {
                    return val.first != detail::Classifier::POSITIONAL_MARK;
                }));

        if (recurse) {
            for (const App_p &sub: subcommands_) {
                remaining_options += sub->remaining_size(recurse);
            }
        }
        return remaining_options;
    }

    void App::_validate() const {
        // count the number of positional only args
        auto pcount = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
            return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional();
        });
        if (pcount > 1) {
            auto pcount_req = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
                return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional() &&
                       opt->get_required();
            });
            if (pcount - pcount_req > 1) {
                throw InvalidError(name_);
            }
        }

        std::size_t nameless_subs{0};
        for (const App_p &app: subcommands_) {
            app->_validate();
            if (app->get_name().empty())
                ++nameless_subs;
        }

        if (require_option_min_ > 0) {
            if (require_option_max_ > 0) {
                if (require_option_max_ < require_option_min_) {
                    throw (InvalidError("Required min options greater than required max options",
                                        ExitCodes::InvalidError));
                }
            }
            if (require_option_min_ > (options_.size() + nameless_subs)) {
                throw (
                        InvalidError("Required min options greater than number of available options",
                                     ExitCodes::InvalidError));
            }
        }
    }

    void App::_configure() {
        if (default_startup == startup_mode::enabled) {
            disabled_ = false;
        } else if (default_startup == startup_mode::disabled) {
            disabled_ = true;
        }
        for (const App_p &app: subcommands_) {
            if (app->has_automatic_name_) {
                app->name_.clear();
            }
            if (app->name_.empty()) {
                app->fallthrough_ = false;  // make sure fallthrough_ is false to prevent infinite loop
                app->prefix_command_ = false;
            }
            // make sure the parent is set to be this object in preparation for parse
            app->parent_ = this;
            app->_configure();
        }
    }

    void App::run_callback(bool final_mode, bool suppress_final_callback) {
        pre_callback();
        // in the main app if immediate_callback_ is set it runs the main callback before the used subcommands
        if (!final_mode && parse_complete_callback_) {
            parse_complete_callback_();
        }
        // run the callbacks for the received subcommands
        for (App *subc: get_subcommands()) {
            if (subc->parent_ == this) {
                subc->run_callback(true, suppress_final_callback);
            }
        }
        // now run callbacks for option_groups
        for (auto &subc: subcommands_) {
            if (subc->name_.empty() && subc->count_all() > 0) {
                subc->run_callback(true, suppress_final_callback);
            }
        }

        // finally run the main callback
        if (final_callback_ && (parsed_ > 0) && (!suppress_final_callback)) {
            if (!name_.empty() || count_all() > 0 || parent_ == nullptr) {
                final_callback_();
            }
        }
    }

    [[nodiscard]] bool App::_valid_subcommand(const std::string &current, bool ignore_used) const {
        // Don't match if max has been reached - but still check parents
        if (require_subcommand_max_ != 0 && parsed_subcommands_.size() >= require_subcommand_max_) {
            return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
        }
        auto *com = _find_subcommand(current, true, ignore_used);
        if (com != nullptr) {
            return true;
        }
        // Check parent if exists, else return false
        return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
    }

    [[nodiscard]] detail::Classifier App::_recognize(const std::string &current,
                                                     bool ignore_used_subcommands) const {
        std::string dummy1, dummy2;

        if (current == "--")
            return detail::Classifier::POSITIONAL_MARK;
        if (_valid_subcommand(current, ignore_used_subcommands))
            return detail::Classifier::SUBCOMMAND;
        if (detail::split_long(current, dummy1, dummy2))
            return detail::Classifier::LONG;
        if (detail::split_short(current, dummy1, dummy2)) {
            if (dummy1[0] >= '0' && dummy1[0] <= '9') {
                if (get_option_no_throw(std::string{'-', dummy1[0]}) == nullptr) {
                    return detail::Classifier::NONE;
                }
            }
            return detail::Classifier::SHORT;
        }
        if ((allow_windows_style_options_) && (detail::split_windows_style(current, dummy1, dummy2)))
            return detail::Classifier::WINDOWS_STYLE;
        if ((current == "++") && !name_.empty() && parent_ != nullptr)
            return detail::Classifier::SUBCOMMAND_TERMINATOR;
        auto dotloc = current.find_first_of('.');
        if (dotloc != std::string::npos) {
            auto *cm = _find_subcommand(current.substr(0, dotloc), true, ignore_used_subcommands);
            if (cm != nullptr) {
                auto res = cm->_recognize(current.substr(dotloc + 1), ignore_used_subcommands);
                if (res == detail::Classifier::SUBCOMMAND) {
                    return res;
                }
            }
        }
        return detail::Classifier::NONE;
    }

    bool App::_process_config_file(const std::string &config_file, bool throw_error) {
        auto path_result = detail::check_path(config_file.c_str());
        if (path_result == detail::path_type::file) {
            try {
                std::vector<ConfigItem> values = config_formatter_->from_file(config_file);
                _parse_config(values);
                return true;
            } catch (const FileError &) {
                if (throw_error) {
                    throw;
                }
                return false;
            }
        } else if (throw_error) {
            throw FileError::Missing(config_file);
        } else {
            return false;
        }
    }

    void App::_process_config_file() {
        if (config_ptr_ != nullptr) {
            bool config_required = config_ptr_->get_required();
            auto file_given = config_ptr_->count() > 0;
            if (!(file_given || config_ptr_->envname_.empty())) {
                std::string ename_string = detail::get_environment_value(config_ptr_->envname_);
                if (!ename_string.empty()) {
                    config_ptr_->add_result(ename_string);
                }
            }
            config_ptr_->run_callback();

            auto config_files = config_ptr_->as<std::vector<std::string>>();
            bool files_used{file_given};
            if (config_files.empty() || config_files.front().empty()) {
                if (config_required) {
                    throw FileError("config file is required but none was given");
                }
                return;
            }
            for (const auto &config_file: config_files) {
                if (_process_config_file(config_file, config_required || file_given)) {
                    files_used = true;
                }
            }
            if (!files_used) {
                // this is done so the count shows as 0 if no callbacks were processed
                config_ptr_->clear();
                bool force = config_ptr_->force_callback_;
                config_ptr_->force_callback_ = false;
                config_ptr_->run_callback();
                config_ptr_->force_callback_ = force;
            }
        }
    }

    void App::_process_env() {
        for (const Option_p &opt: options_) {
            if (opt->count() == 0 && !opt->envname_.empty()) {
                std::string ename_string = detail::get_environment_value(opt->envname_);
                if (!ename_string.empty()) {
                    std::string result = ename_string;
                    result = opt->_validate(result, 0);
                    if (result.empty()) {
                        opt->add_result(ename_string);
                    }
                }
            }
        }

        for (App_p &sub: subcommands_) {
            if (sub->get_name().empty() || (sub->count_all() > 0 && !sub->parse_complete_callback_)) {
                // only process environment variables if the callback has actually been triggered already
                sub->_process_env();
            }
        }
    }

    void App::_process_callbacks() {

        for (App_p &sub: subcommands_) {
            // process the priority option_groups first
            if (sub->get_name().empty() && sub->parse_complete_callback_) {
                if (sub->count_all() > 0) {
                    sub->_process_callbacks();
                    sub->run_callback();
                }
            }
        }

        for (const Option_p &opt: options_) {
            if ((*opt) && !opt->get_callback_run()) {
                opt->run_callback();
            }
        }
        for (App_p &sub: subcommands_) {
            if (!sub->parse_complete_callback_) {
                sub->_process_callbacks();
            }
        }
    }

    void App::_process_help_flags(bool trigger_help, bool trigger_all_help) const {
        const Option *help_ptr = get_help_ptr();
        const Option *help_all_ptr = get_help_all_ptr();

        if (help_ptr != nullptr && help_ptr->count() > 0)
            trigger_help = true;
        if (help_all_ptr != nullptr && help_all_ptr->count() > 0)
            trigger_all_help = true;

        // If there were parsed subcommands, call those. First subcommand wins if there are multiple ones.
        if (!parsed_subcommands_.empty()) {
            for (const App *sub: parsed_subcommands_)
                sub->_process_help_flags(trigger_help, trigger_all_help);

            // Only the final subcommand should call for help. All help wins over help.
        } else if (trigger_all_help) {
            throw CallForAllHelp();
        } else if (trigger_help) {
            throw CallForHelp();
        }
    }

    void App::_process_requirements() {
        // check excludes
        bool excluded{false};
        std::string excluder;
        for (const auto &opt: exclude_options_) {
            if (opt->count() > 0) {
                excluded = true;
                excluder = opt->get_name();
            }
        }
        for (const auto &subc: exclude_subcommands_) {
            if (subc->count_all() > 0) {
                excluded = true;
                excluder = subc->get_display_name();
            }
        }
        if (excluded) {
            if (count_all() > 0) {
                throw ExcludesError(get_display_name(), excluder);
            }
            // if we are excluded but didn't receive anything, just return
            return;
        }

        // check excludes
        bool missing_needed{false};
        std::string missing_need;
        for (const auto &opt: need_options_) {
            if (opt->count() == 0) {
                missing_needed = true;
                missing_need = opt->get_name();
            }
        }
        for (const auto &subc: need_subcommands_) {
            if (subc->count_all() == 0) {
                missing_needed = true;
                missing_need = subc->get_display_name();
            }
        }
        if (missing_needed) {
            if (count_all() > 0) {
                throw RequiresError(get_display_name(), missing_need);
            }
            // if we missing something but didn't have any options, just return
            return;
        }

        std::size_t used_options = 0;
        for (const Option_p &opt: options_) {

            if (opt->count() != 0) {
                ++used_options;
            }
            // Required but empty
            if (opt->get_required() && opt->count() == 0) {
                throw RequiredError(opt->get_name());
            }
            // Requires
            for (const Option *opt_req: opt->needs_)
                if (opt->count() > 0 && opt_req->count() == 0)
                    throw RequiresError(opt->get_name(), opt_req->get_name());
            // Excludes
            for (const Option *opt_ex: opt->excludes_)
                if (opt->count() > 0 && opt_ex->count() != 0)
                    throw ExcludesError(opt->get_name(), opt_ex->get_name());
        }
        // check for the required number of subcommands
        if (require_subcommand_min_ > 0) {
            auto selected_subcommands = get_subcommands();
            if (require_subcommand_min_ > selected_subcommands.size())
                throw RequiredError::Subcommand(require_subcommand_min_);
        }

        // Max error cannot occur, the extra subcommand will parse as an ExtrasError or a remaining item.

        // run this loop to check how many unnamed subcommands were actually used since they are considered options
        // from the perspective of an App
        for (App_p &sub: subcommands_) {
            if (sub->disabled_)
                continue;
            if (sub->name_.empty() && sub->count_all() > 0) {
                ++used_options;
            }
        }

        if (require_option_min_ > used_options || (require_option_max_ > 0 && require_option_max_ < used_options)) {
            auto option_list = detail::join(options_, [this](const Option_p &ptr) {
                if (ptr.get() == help_ptr_ || ptr.get() == help_all_ptr_) {
                    return std::string{};
                }
                return ptr->get_name(false, true);
            });

            auto subc_list = get_subcommands([](App *app) { return ((app->get_name().empty()) && (!app->disabled_)); });
            if (!subc_list.empty()) {
                option_list += "," + detail::join(subc_list, [](const App *app) { return app->get_display_name(); });
            }
            throw RequiredError::Option(require_option_min_, require_option_max_, used_options, option_list);
        }

        // now process the requirements for subcommands if needed
        for (App_p &sub: subcommands_) {
            if (sub->disabled_)
                continue;
            if (sub->name_.empty() && sub->required_ == false) {
                if (sub->count_all() == 0) {
                    if (require_option_min_ > 0 && require_option_min_ <= used_options) {
                        continue;
                        // if we have met the requirement and there is nothing in this option group skip checking
                        // requirements
                    }
                    if (require_option_max_ > 0 && used_options >= require_option_min_) {
                        continue;
                        // if we have met the requirement and there is nothing in this option group skip checking
                        // requirements
                    }
                }
            }
            if (sub->count() > 0 || sub->name_.empty()) {
                sub->_process_requirements();
            }

            if (sub->required_ && sub->count_all() == 0) {
                throw (turbo::cli::RequiredError(sub->get_display_name()));
            }
        }
    }

    void App::_process() {
        try {
            // the config file might generate a FileError but that should not be processed until later in the process
            // to allow for help, version and other errors to generate first.
            _process_config_file();

            // process env shouldn't throw but no reason to process it if config generated an error
            _process_env();
        } catch (const turbo::cli::FileError &) {
            // callbacks and help_flags can generate exceptions which should take priority
            // over the config file error if one exists.
            _process_callbacks();
            _process_help_flags();
            throw;
        }

        _process_callbacks();
        _process_help_flags();

        _process_requirements();
    }

    void App::_process_extras() {
        if (!(allow_extras_ || prefix_command_)) {
            std::size_t num_left_over = remaining_size();
            if (num_left_over > 0) {
                throw ExtrasError(name_, remaining(false));
            }
        }

        for (App_p &sub: subcommands_) {
            if (sub->count() > 0)
                sub->_process_extras();
        }
    }

    void App::_process_extras(std::vector<std::string> &args) {
        if (!(allow_extras_ || prefix_command_)) {
            std::size_t num_left_over = remaining_size();
            if (num_left_over > 0) {
                args = remaining(false);
                throw ExtrasError(name_, args);
            }
        }

        for (App_p &sub: subcommands_) {
            if (sub->count() > 0)
                sub->_process_extras(args);
        }
    }

    void App::increment_parsed() {
        ++parsed_;
        for (App_p &sub: subcommands_) {
            if (sub->get_name().empty())
                sub->increment_parsed();
        }
    }

    void App::_parse(std::vector<std::string> &args) {
        increment_parsed();
        _trigger_pre_parse(args.size());
        bool positional_only = false;

        while (!args.empty()) {
            if (!_parse_single(args, positional_only)) {
                break;
            }
        }

        if (parent_ == nullptr) {
            _process();

            // Throw error if any items are left over (depending on settings)
            _process_extras(args);

            // Convert missing (pairs) to extras (string only) ready for processing in another app
            args = remaining_for_passthrough(false);
        } else if (parse_complete_callback_) {
            _process_env();
            _process_callbacks();
            _process_help_flags();
            _process_requirements();
            run_callback(false, true);
        }
    }

    void App::_parse(std::vector<std::string> &&args) {
        // this can only be called by the top level in which case parent == nullptr by definition
        // operation is simplified
        increment_parsed();
        _trigger_pre_parse(args.size());
        bool positional_only = false;

        while (!args.empty()) {
            _parse_single(args, positional_only);
        }
        _process();

        // Throw error if any items are left over (depending on settings)
        _process_extras();
    }

    void App::_parse_stream(std::istream &input) {
        auto values = config_formatter_->from_config(input);
        _parse_config(values);
        increment_parsed();
        _trigger_pre_parse(values.size());
        _process();

        // Throw error if any items are left over (depending on settings)
        _process_extras();
    }

    void App::_parse_config(const std::vector<ConfigItem> &args) {
        for (const ConfigItem &item: args) {
            if (!_parse_single_config(item) && allow_config_extras_ == config_extras_mode::error)
                throw ConfigError::Extras(item.fullname());
        }
    }

    bool App::_parse_single_config(const ConfigItem &item, std::size_t level) {

        if (level < item.parents.size()) {
            auto *subcom = get_subcommand_no_throw(item.parents.at(level));
            return (subcom != nullptr) ? subcom->_parse_single_config(item, level + 1) : false;
        }
        // check for section open
        if (item.name == "++") {
            if (configurable_) {
                increment_parsed();
                _trigger_pre_parse(2);
                if (parent_ != nullptr) {
                    parent_->parsed_subcommands_.push_back(this);
                }
            }
            return true;
        }
        // check for section close
        if (item.name == "--") {
            if (configurable_ && parse_complete_callback_) {
                _process_callbacks();
                _process_requirements();
                run_callback();
            }
            return true;
        }
        Option *op = get_option_no_throw("--" + item.name);
        if (op == nullptr) {
            if (item.name.size() == 1) {
                op = get_option_no_throw("-" + item.name);
            }
            if (op == nullptr) {
                op = get_option_no_throw(item.name);
            }
        }

        if (op == nullptr) {
            // If the option was not present
            if (get_allow_config_extras() == config_extras_mode::capture) {
                // Should we worry about classifying the extras properly?
                missing_.emplace_back(detail::Classifier::NONE, item.fullname());
                for (const auto &input: item.inputs) {
                    missing_.emplace_back(detail::Classifier::NONE, input);
                }
            }
            return false;
        }

        if (!op->get_configurable()) {
            if (get_allow_config_extras() == config_extras_mode::ignore_all) {
                return false;
            }
            throw ConfigError::NotConfigurable(item.fullname());
        }

        if (op->empty()) {

            if (op->get_expected_min() == 0) {
                if (item.inputs.size() <= 1) {
                    // Flag parsing
                    auto res = config_formatter_->to_flag(item);
                    bool converted{false};
                    if (op->get_disable_flag_override()) {
                        auto val = detail::to_flag_value(res);
                        if (val == 1) {
                            res = op->get_flag_value(item.name, "{}");
                            converted = true;
                        }
                    }

                    if (!converted) {
                        errno = 0;
                        res = op->get_flag_value(item.name, res);
                    }

                    op->add_result(res);
                    return true;
                }
                if (static_cast<int>(item.inputs.size()) > op->get_items_expected_max() &&
                    op->get_multi_option_policy() != MultiOptionPolicy::TakeAll) {
                    if (op->get_items_expected_max() > 1) {
                        throw ArgumentMismatch::AtMost(item.fullname(), op->get_items_expected_max(),
                                                       item.inputs.size());
                    }

                    if (!op->get_disable_flag_override()) {
                        throw ConversionError::TooManyInputsFlag(item.fullname());
                    }
                    // if the disable flag override is set then we must have the flag values match a known flag value
                    // this is true regardless of the output value, so an array input is possible and must be accounted for
                    for (const auto &res: item.inputs) {
                        bool valid_value{false};
                        if (op->default_flag_values_.empty()) {
                            if (res == "true" || res == "false" || res == "1" || res == "0") {
                                valid_value = true;
                            }
                        } else {
                            for (const auto &valid_res: op->default_flag_values_) {
                                if (valid_res.second == res) {
                                    valid_value = true;
                                    break;
                                }
                            }
                        }

                        if (valid_value) {
                            op->add_result(res);
                        } else {
                            throw InvalidError("invalid flag argument given");
                        }
                    }
                    return true;
                }
            }
            op->add_result(item.inputs);
            op->run_callback();
        }

        return true;
    }

    bool App::_parse_single(std::vector<std::string> &args, bool &positional_only) {
        bool retval = true;
        detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
        switch (classifier) {
            case detail::Classifier::POSITIONAL_MARK:
                args.pop_back();
                positional_only = true;
                if ((!_has_remaining_positionals()) && (parent_ != nullptr)) {
                    retval = false;
                } else {
                    _move_to_missing(classifier, "--");
                }
                break;
            case detail::Classifier::SUBCOMMAND_TERMINATOR:
                // treat this like a positional mark if in the parent app
                args.pop_back();
                retval = false;
                break;
            case detail::Classifier::SUBCOMMAND:
                retval = _parse_subcommand(args);
                break;
            case detail::Classifier::LONG:
            case detail::Classifier::SHORT:
            case detail::Classifier::WINDOWS_STYLE:
                // If already parsed a subcommand, don't accept options_
                retval = _parse_arg(args, classifier, false);
                break;
            case detail::Classifier::NONE:
                // Probably a positional or something for a parent (sub)command
                retval = _parse_positional(args, false);
                if (retval && positionals_at_end_) {
                    positional_only = true;
                }
                break;
                // LCOV_EXCL_START
            default:
                throw HorribleError("unrecognized classifier (you should not see this!)");
                // LCOV_EXCL_STOP
        }
        return retval;
    }

    [[nodiscard]] std::size_t App::_count_remaining_positionals(bool required_only) const {
        std::size_t retval = 0;
        for (const Option_p &opt: options_) {
            if (opt->get_positional() && (!required_only || opt->get_required())) {
                if (opt->get_items_expected_min() > 0 &&
                    static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
                    retval += static_cast<std::size_t>(opt->get_items_expected_min()) - opt->count();
                }
            }
        }
        return retval;
    }

    [[nodiscard]] bool App::_has_remaining_positionals() const {
        for (const Option_p &opt: options_) {
            if (opt->get_positional() && ((static_cast<int>(opt->count()) < opt->get_items_expected_min()))) {
                return true;
            }
        }

        return false;
    }

    bool App::_parse_positional(std::vector<std::string> &args, bool haltOnSubcommand) {

        const std::string &positional = args.back();
        Option *posOpt{nullptr};

        if (positionals_at_end_) {
            // deal with the case of required arguments at the end which should take precedence over other arguments
            auto arg_rem = args.size();
            auto remreq = _count_remaining_positionals(true);
            if (arg_rem <= remreq) {
                for (const Option_p &opt: options_) {
                    if (opt->get_positional() && opt->required_) {
                        if (static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
                            if (validate_positionals_) {
                                std::string pos = positional;
                                pos = opt->_validate(pos, 0);
                                if (!pos.empty()) {
                                    continue;
                                }
                            }
                            posOpt = opt.get();
                            break;
                        }
                    }
                }
            }
        }
        if (posOpt == nullptr) {
            for (const Option_p &opt: options_) {
                // Eat options, one by one, until done
                if (opt->get_positional() &&
                    (static_cast<int>(opt->count()) < opt->get_items_expected_min() || opt->get_allow_extra_args())) {
                    if (validate_positionals_) {
                        std::string pos = positional;
                        pos = opt->_validate(pos, 0);
                        if (!pos.empty()) {
                            continue;
                        }
                    }
                    posOpt = opt.get();
                    break;
                }
            }
        }
        if (posOpt != nullptr) {
            parse_order_.push_back(posOpt);
            if (posOpt->get_inject_separator()) {
                if (!posOpt->results().empty() && !posOpt->results().back().empty()) {
                    posOpt->add_result(std::string{});
                }
            }
            if (posOpt->get_trigger_on_parse() && posOpt->current_option_state_ == Option::option_state::callback_run) {
                posOpt->clear();
            }
            posOpt->add_result(positional);
            if (posOpt->get_trigger_on_parse()) {
                posOpt->run_callback();
            }

            args.pop_back();
            return true;
        }

        for (auto &subc: subcommands_) {
            if ((subc->name_.empty()) && (!subc->disabled_)) {
                if (subc->_parse_positional(args, false)) {
                    if (!subc->pre_parse_called_) {
                        subc->_trigger_pre_parse(args.size());
                    }
                    return true;
                }
            }
        }
        // let the parent deal with it if possible
        if (parent_ != nullptr && fallthrough_)
            return _get_fallthrough_parent()->_parse_positional(args, static_cast<bool>(parse_complete_callback_));

        /// Try to find a local subcommand that is repeated
        auto *com = _find_subcommand(args.back(), true, false);
        if (com != nullptr && (require_subcommand_max_ == 0 || require_subcommand_max_ > parsed_subcommands_.size())) {
            if (haltOnSubcommand) {
                return false;
            }
            args.pop_back();
            com->_parse(args);
            return true;
        }
        /// now try one last gasp at subcommands that have been executed before, go to root app and try to find a
        /// subcommand in a broader way, if one exists let the parent deal with it
        auto *parent_app = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
        com = parent_app->_find_subcommand(args.back(), true, false);
        if (com != nullptr && (com->parent_->require_subcommand_max_ == 0 ||
                               com->parent_->require_subcommand_max_ > com->parent_->parsed_subcommands_.size())) {
            return false;
        }

        if (positionals_at_end_) {
            throw turbo::cli::ExtrasError(name_, args);
        }
        /// If this is an option group don't deal with it
        if (parent_ != nullptr && name_.empty()) {
            return false;
        }
        /// We are out of other options this goes to missing
        _move_to_missing(detail::Classifier::NONE, positional);
        args.pop_back();
        if (prefix_command_) {
            while (!args.empty()) {
                _move_to_missing(detail::Classifier::NONE, args.back());
                args.pop_back();
            }
        }

        return true;
    }

    [[nodiscard]] App *
    App::_find_subcommand(const std::string &subc_name, bool ignore_disabled, bool ignore_used) const noexcept {
        for (const App_p &com: subcommands_) {
            if (com->disabled_ && ignore_disabled)
                continue;
            if (com->get_name().empty()) {
                auto *subc = com->_find_subcommand(subc_name, ignore_disabled, ignore_used);
                if (subc != nullptr) {
                    return subc;
                }
            }
            if (com->check_name(subc_name)) {
                if ((!*com) || !ignore_used)
                    return com.get();
            }
        }
        return nullptr;
    }

    bool App::_parse_subcommand(std::vector<std::string> &args) {
        if (_count_remaining_positionals(/* required */ true) > 0) {
            _parse_positional(args, false);
            return true;
        }
        auto *com = _find_subcommand(args.back(), true, true);
        if (com == nullptr) {
            // the main way to get here is using .notation
            auto dotloc = args.back().find_first_of('.');
            if (dotloc != std::string::npos) {
                com = _find_subcommand(args.back().substr(0, dotloc), true, true);
                if (com != nullptr) {
                    args.back() = args.back().substr(dotloc + 1);
                    args.push_back(com->get_display_name());
                }
            }
        }
        if (com != nullptr) {
            args.pop_back();
            if (!com->silent_) {
                parsed_subcommands_.push_back(com);
            }
            com->_parse(args);
            auto *parent_app = com->parent_;
            while (parent_app != this) {
                parent_app->_trigger_pre_parse(args.size());
                if (!com->silent_) {
                    parent_app->parsed_subcommands_.push_back(com);
                }
                parent_app = parent_app->parent_;
            }
            return true;
        }

        if (parent_ == nullptr)
            throw HorribleError("Subcommand " + args.back() + " missing");
        return false;
    }

    bool
    App::_parse_arg(std::vector<std::string> &args, detail::Classifier current_type, bool local_processing_only) {

        std::string current = args.back();

        std::string arg_name;
        std::string value;
        std::string rest;

        switch (current_type) {
            case detail::Classifier::LONG:
                if (!detail::split_long(current, arg_name, value))
                    throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
                break;
            case detail::Classifier::SHORT:
                if (!detail::split_short(current, arg_name, rest))
                    throw HorribleError("Short parsed but missing! You should not see this");
                break;
            case detail::Classifier::WINDOWS_STYLE:
                if (!detail::split_windows_style(current, arg_name, value))
                    throw HorribleError("windows option parsed but missing! You should not see this");
                break;
            case detail::Classifier::SUBCOMMAND:
            case detail::Classifier::SUBCOMMAND_TERMINATOR:
            case detail::Classifier::POSITIONAL_MARK:
            case detail::Classifier::NONE:
            default:
                throw HorribleError("parsing got called with invalid option! You should not see this");
        }

        auto op_ptr = std::find_if(std::begin(options_), std::end(options_),
                                   [arg_name, current_type](const Option_p &opt) {
                                       if (current_type == detail::Classifier::LONG)
                                           return opt->check_lname(arg_name);
                                       if (current_type == detail::Classifier::SHORT)
                                           return opt->check_sname(arg_name);
                                       // this will only get called for detail::Classifier::WINDOWS_STYLE
                                       return opt->check_lname(arg_name) || opt->check_sname(arg_name);
                                   });

        // Option not found
        if (op_ptr == std::end(options_)) {
            for (auto &subc: subcommands_) {
                if (subc->name_.empty() && !subc->disabled_) {
                    if (subc->_parse_arg(args, current_type, local_processing_only)) {
                        if (!subc->pre_parse_called_) {
                            subc->_trigger_pre_parse(args.size());
                        }
                        return true;
                    }
                }
            }

            // don't capture missing if this is a nameless subcommand and nameless subcommands can't fallthrough
            if (parent_ != nullptr && name_.empty()) {
                return false;
            }

            // now check for '.' notation of subcommands
            auto dotloc = arg_name.find_first_of('.', 1);
            if (dotloc != std::string::npos) {
                // using dot notation is equivalent to single argument subcommand
                auto *sub = _find_subcommand(arg_name.substr(0, dotloc), true, false);
                if (sub != nullptr) {
                    auto v = args.back();
                    args.pop_back();
                    arg_name = arg_name.substr(dotloc + 1);
                    if (arg_name.size() > 1) {
                        args.push_back(std::string("--") + v.substr(dotloc + 3));
                        current_type = detail::Classifier::LONG;
                    } else {
                        auto nval = v.substr(dotloc + 2);
                        nval.front() = '-';
                        if (nval.size() > 2) {
                            // '=' not allowed in short form arguments
                            args.push_back(nval.substr(3));
                            nval.resize(2);
                        }
                        args.push_back(nval);
                        current_type = detail::Classifier::SHORT;
                    }
                    auto val = sub->_parse_arg(args, current_type, true);
                    if (val) {
                        if (!sub->silent_) {
                            parsed_subcommands_.push_back(sub);
                        }
                        // deal with preparsing
                        increment_parsed();
                        _trigger_pre_parse(args.size());
                        // run the parse complete callback since the subcommand processing is now complete
                        if (sub->parse_complete_callback_) {
                            sub->_process_env();
                            sub->_process_callbacks();
                            sub->_process_help_flags();
                            sub->_process_requirements();
                            sub->run_callback(false, true);
                        }
                        return true;
                    }
                    args.pop_back();
                    args.push_back(v);
                }
            }
            if (local_processing_only) {
                return false;
            }
            // If a subcommand, try the main command
            if (parent_ != nullptr && fallthrough_)
                return _get_fallthrough_parent()->_parse_arg(args, current_type, false);

            // Otherwise, add to missing
            args.pop_back();
            _move_to_missing(current_type, current);
            return true;
        }

        args.pop_back();

        // Get a reference to the pointer to make syntax bearable
        Option_p &op = *op_ptr;
        /// if we require a separator add it here
        if (op->get_inject_separator()) {
            if (!op->results().empty() && !op->results().back().empty()) {
                op->add_result(std::string{});
            }
        }
        if (op->get_trigger_on_parse() && op->current_option_state_ == Option::option_state::callback_run) {
            op->clear();
        }
        int min_num = (std::min)(op->get_type_size_min(), op->get_items_expected_min());
        int max_num = op->get_items_expected_max();
        // check container like options to limit the argument size to a single type if the allow_extra_flags argument is
        // set. 16 is somewhat arbitrary (needs to be at least 4)
        if (max_num >= detail::expected_max_vector_size / 16 && !op->get_allow_extra_args()) {
            auto tmax = op->get_type_size_max();
            max_num = detail::checked_multiply(tmax, op->get_expected_min()) ? tmax : detail::expected_max_vector_size;
        }
        // Make sure we always eat the minimum for unlimited vectors
        int collected = 0;     // total number of arguments collected
        int result_count = 0;  // local variable for number of results in a single arg string
        // deal with purely flag like things
        if (max_num == 0) {
            auto res = op->get_flag_value(arg_name, value);
            op->add_result(res);
            parse_order_.push_back(op.get());
        } else if (!value.empty()) {  // --this=value
            op->add_result(value, result_count);
            parse_order_.push_back(op.get());
            collected += result_count;
            // -Trest
        } else if (!rest.empty()) {
            op->add_result(rest, result_count);
            parse_order_.push_back(op.get());
            rest = "";
            collected += result_count;
        }

        // gather the minimum number of arguments
        while (min_num > collected && !args.empty()) {
            std::string current_ = args.back();
            args.pop_back();
            op->add_result(current_, result_count);
            parse_order_.push_back(op.get());
            collected += result_count;
        }

        if (min_num > collected) {  // if we have run out of arguments and the minimum was not met
            throw ArgumentMismatch::TypedAtLeast(op->get_name(), min_num, op->get_type_name());
        }

        // now check for optional arguments
        if (max_num > collected || op->get_allow_extra_args()) {  // we allow optional arguments
            auto remreqpos = _count_remaining_positionals(true);
            // we have met the minimum now optionally check up to the maximum
            while ((collected < max_num || op->get_allow_extra_args()) && !args.empty() &&
                   _recognize(args.back(), false) == detail::Classifier::NONE) {
                // If any required positionals remain, don't keep eating
                if (remreqpos >= args.size()) {
                    break;
                }
                if (validate_optional_arguments_) {
                    std::string arg = args.back();
                    arg = op->_validate(arg, 0);
                    if (!arg.empty()) {
                        break;
                    }
                }
                op->add_result(args.back(), result_count);
                parse_order_.push_back(op.get());
                args.pop_back();
                collected += result_count;
            }

            // Allow -- to end an unlimited list and "eat" it
            if (!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
                args.pop_back();
            // optional flag that didn't receive anything now get the default value
            if (min_num == 0 && max_num > 0 && collected == 0) {
                auto res = op->get_flag_value(arg_name, std::string{});
                op->add_result(res);
                parse_order_.push_back(op.get());
            }
        }
        // if we only partially completed a type then add an empty string if allowed for later processing
        if (min_num > 0 && (collected % op->get_type_size_max()) != 0) {
            if (op->get_type_size_max() != op->get_type_size_min()) {
                op->add_result(std::string{});
            } else {
                throw ArgumentMismatch::PartialType(op->get_name(), op->get_type_size_min(), op->get_type_name());
            }
        }
        if (op->get_trigger_on_parse()) {
            op->run_callback();
        }
        if (!rest.empty()) {
            rest = "-" + rest;
            args.push_back(rest);
        }
        return true;
    }

    void App::_trigger_pre_parse(std::size_t remaining_args) {
        if (!pre_parse_called_) {
            pre_parse_called_ = true;
            if (pre_parse_callback_) {
                pre_parse_callback_(remaining_args);
            }
        } else if (immediate_callback_) {
            if (!name_.empty()) {
                auto pcnt = parsed_;
                missing_t extras = std::move(missing_);
                clear();
                parsed_ = pcnt;
                pre_parse_called_ = true;
                missing_ = std::move(extras);
            }
        }
    }

    App *App::_get_fallthrough_parent() {
        if (parent_ == nullptr) {
            throw (HorribleError("No Valid parent"));
        }
        auto *fallthrough_parent = parent_;
        while ((fallthrough_parent->parent_ != nullptr) && (fallthrough_parent->get_name().empty())) {
            fallthrough_parent = fallthrough_parent->parent_;
        }
        return fallthrough_parent;
    }

    [[nodiscard]] const std::string &App::_compare_subcommand_names(const App &subcom,
                                                                    const App &base) const {
        static const std::string estring;
        if (subcom.disabled_) {
            return estring;
        }
        for (const auto &subc: base.subcommands_) {
            if (subc.get() != &subcom) {
                if (subc->disabled_) {
                    continue;
                }
                if (!subcom.get_name().empty()) {
                    if (subc->check_name(subcom.get_name())) {
                        return subcom.get_name();
                    }
                }
                if (!subc->get_name().empty()) {
                    if (subcom.check_name(subc->get_name())) {
                        return subc->get_name();
                    }
                }
                for (const auto &les: subcom.aliases_) {
                    if (subc->check_name(les)) {
                        return les;
                    }
                }
                // this loop is needed in case of ignore_underscore or ignore_case on one but not the other
                for (const auto &les: subc->aliases_) {
                    if (subcom.check_name(les)) {
                        return les;
                    }
                }
                // if the subcommand is an option group we need to check deeper
                if (subc->get_name().empty()) {
                    const auto &cmpres = _compare_subcommand_names(subcom, *subc);
                    if (!cmpres.empty()) {
                        return cmpres;
                    }
                }
                // if the test subcommand is an option group we need to check deeper
                if (subcom.get_name().empty()) {
                    const auto &cmpres = _compare_subcommand_names(*subc, subcom);
                    if (!cmpres.empty()) {
                        return cmpres;
                    }
                }
            }
        }
        return estring;
    }

    void App::_move_to_missing(detail::Classifier val_type, const std::string &val) {
        if (allow_extras_ || subcommands_.empty()) {
            missing_.emplace_back(val_type, val);
            return;
        }
        // allow extra arguments to be places in an option group if it is allowed there
        for (auto &subc: subcommands_) {
            if (subc->name_.empty() && subc->allow_extras_) {
                subc->missing_.emplace_back(val_type, val);
                return;
            }
        }
        // if we haven't found any place to put them yet put them in missing
        missing_.emplace_back(val_type, val);
    }

    void App::_move_option(Option *opt, App *app) {
        if (opt == nullptr) {
            throw OptionNotFound("the option is NULL");
        }
        // verify that the give app is actually a subcommand
        bool found = false;
        for (auto &subc: subcommands_) {
            if (app == subc.get()) {
                found = true;
            }
        }
        if (!found) {
            throw OptionNotFound("The Given app is not a subcommand");
        }

        if ((help_ptr_ == opt) || (help_all_ptr_ == opt))
            throw OptionAlreadyAdded("cannot move help options");

        if (config_ptr_ == opt)
            throw OptionAlreadyAdded("cannot move config file options");

        auto iterator =
                std::find_if(std::begin(options_), std::end(options_),
                             [opt](const Option_p &v) { return v.get() == opt; });
        if (iterator != std::end(options_)) {
            const auto &opt_p = *iterator;
            if (std::find_if(std::begin(app->options_), std::end(app->options_), [&opt_p](const Option_p &v) {
                return (*v == *opt_p);
            }) == std::end(app->options_)) {
                // only erase after the insertion was successful
                app->options_.push_back(std::move(*iterator));
                options_.erase(iterator);
            } else {
                throw OptionAlreadyAdded("option was not located: " + opt->get_name());
            }
        } else {
            throw OptionNotFound("could not locate the given Option");
        }
    }

    void TriggerOn(App *trigger_app, App *app_to_enable) {
        app_to_enable->enabled_by_default(false);
        app_to_enable->disabled_by_default();
        trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(false); });
    }

    void TriggerOn(App *trigger_app, std::vector<App *> apps_to_enable) {
        for (auto &app: apps_to_enable) {
            app->enabled_by_default(false);
            app->disabled_by_default();
        }

        trigger_app->preparse_callback([apps_to_enable](std::size_t) {
            for (const auto &app: apps_to_enable) {
                app->disabled(false);
            }
        });
    }

    void TriggerOff(App *trigger_app, App *app_to_enable) {
        app_to_enable->disabled_by_default(false);
        app_to_enable->enabled_by_default();
        trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(); });
    }

    void TriggerOff(App *trigger_app, std::vector<App *> apps_to_enable) {
        for (auto &app: apps_to_enable) {
            app->disabled_by_default(false);
            app->enabled_by_default();
        }

        trigger_app->preparse_callback([apps_to_enable](std::size_t) {
            for (const auto &app: apps_to_enable) {
                app->disabled();
            }
        });
    }

    void deprecate_option(Option *opt, const std::string &replacement) {
        Validator deprecate_warning{[opt, replacement](std::string &) {
            std::cout << opt->get_name() << " is deprecated please use '" << replacement
                      << "' instead\n";
            return std::string();
        },
                                    "DEPRECATED"};
        deprecate_warning.application_index(0);
        opt->check(deprecate_warning);
        if (!replacement.empty()) {
            opt->description(opt->get_description() + " DEPRECATED: please use '" + replacement + "' instead");
        }
    }

    void retire_option(App *app, Option *opt) {
        App temp;
        auto *option_copy = temp.add_option(opt->get_name(false, true))
                ->type_size(opt->get_type_size_min(), opt->get_type_size_max())
                ->expected(opt->get_expected_min(), opt->get_expected_max())
                ->allow_extra_args(opt->get_allow_extra_args());

        app->remove_option(opt);
        auto *opt2 = app->add_option(option_copy->get_name(false, true), "option has been retired and has no effect");
        opt2->type_name("RETIRED")
                ->default_str("RETIRED")
                ->type_size(option_copy->get_type_size_min(), option_copy->get_type_size_max())
                ->expected(option_copy->get_expected_min(), option_copy->get_expected_max())
                ->allow_extra_args(option_copy->get_allow_extra_args());

        Validator retired_warning{[opt2](std::string &) {
            std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
            return std::string();
        },
                                  ""};
        retired_warning.application_index(0);
        opt2->check(retired_warning);
    }

    void retire_option(App &app, Option *opt) { retire_option(&app, opt); }

    void retire_option(App *app, const std::string &option_name) {

        auto *opt = app->get_option_no_throw(option_name);
        if (opt != nullptr) {
            retire_option(app, opt);
            return;
        }
        auto *opt2 = app->add_option(option_name, "option has been retired and has no effect")
                ->type_name("RETIRED")
                ->expected(0, 1)
                ->default_str("RETIRED");
        Validator retired_warning{[opt2](std::string &) {
            std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
            return std::string();
        },
                                  ""};
        retired_warning.application_index(0);
        opt2->check(retired_warning);
    }

    void retire_option(App &app, const std::string &option_name) { retire_option(&app, option_name); }

    namespace FailureMessage {

        std::string simple(const App *app, const Error &e) {
            std::string header = std::string(e.what()) + "\n";
            std::vector<std::string> names;

            // Collect names
            if (app->get_help_ptr() != nullptr)
                names.push_back(app->get_help_ptr()->get_name());

            if (app->get_help_all_ptr() != nullptr)
                names.push_back(app->get_help_all_ptr()->get_name());

            // If any names found, suggest those
            if (!names.empty())
                header += "Run with " + detail::join(names, " or ") + " for more information.\n";

            return header;
        }

        std::string help(const App *app, const Error &e) {
            std::string header = std::string("ERROR: ") + e.get_name() + ": " + e.what() + "\n";
            header += app->help();
            return header;
        }

    }  // namespace FailureMessage

}  // namespace turbo::cli
